Device for treating heart failure

ABSTRACT

A cardiac harness is configured to fit about a portion of a patient&#39;s heart so as to exert a compressive force on the heart during at least a portion of the cardiac cycle. The harness can be constructed of a plurality of individual modules assembled ex vivo or in vivo. The modules can have different physical characteristics, such as having different compliance, and may or may not include spring hinges. Portions of a cardiac harness can be connected to each other using a coupling mechanism such as, for example, a zip coupler.

RELATED APPLICATIONS

[0001] This application claims priority to U.S. Provisional ApplicationNo. 60/322,089, which was filed on Sep. 10, 2001, the entirety of whichis hereby incorporated by reference.

BACKGROUND OF THE INVENTION

[0002] 1. Field of the Invention

[0003] The present invention relates to a device for treating heartfailure. More specifically, the invention relates to a cardiac harnessconfigured to be fit around at least a portion of a patient's heart.

[0004] 2. Description of the Related Art

[0005] Congestive heart failure (“CHF”) is characterized by the failureof the heart to pump blood at sufficient flow rates to meet themetabolic demand of tissues, especially the demand for oxygen. Onecharacteristic of CHF is remodeling of at least portions of a patient'sheart. Remodeling involves physical changes to the size, shape andthickness of the heart wall. For example, a damaged left ventricle mayhave some localized thinning and stretching of a portion of themyocardium. The thinned portion of the myocardium often is functionallyimpaired, and other portions of the myocardium attempt to compensate. Asa result, the other portions of the myocardium may expand so that thestroke volume of the ventricle is maintained notwithstanding theimpaired zone of the myocardium. Such expansion may cause the leftventricle to assume a somewhat spherical shape.

[0006] Cardiac remodeling often subjects the heart wall to increasedwall tension or stress, which further impairs the heart's functionalperformance. Often, the heart wall will dilate further in order tocompensate for the impairment caused by such increased stress. Thus, avicious cycle can result, in which dilation leads to further dilationand greater functional impairment.

[0007] Historically, congestive heart failure has been managed with avariety of drugs. Devices have also been used to improve cardiac output.For example, left ventricular assist pumps help the heart to pump blood.Multi-chamber pacing has also been employed to optimally synchronize thebeating of the heart chambers to improve cardiac output. Variousskeletal muscles, such as the latissimus dorsi, have been used to assistventricular pumping. Researchers and cardiac surgeons have alsoexperimented with prosthetic “girdles” disposed around the heart. Onesuch design is a prosthetic “sock” or “jacket” that is wrapped aroundthe heart.

[0008] Although some of the above-discussed devices hold promise, thereremains a need in the art for a device for treating CHF to prevent aremodeled heart from further remodeling and/or help reverse remodelingof a diseased heart.

SUMMARY OF THE INVENTION

[0009] In accordance with one aspect of the present invention, a cardiacharness is configured to fit about a patient's heart. The harnesscomprises a plurality of individual modules that are assembled togetherto form the harness.

[0010] In accordance with another aspect, the present invention providesa cardiac harness configured to fit about a patient's heart. A firstmodule of the harness extends along a first portion of a circumferenceof the harness. A second module extends along a second portion of thecircumference of the harness. The first and second modules are connectedto one another.

[0011] In accordance with still another aspect, the present inventionprovides a cardiac harness configured to fit about a patient's heart. Azip coupler is configured to selectively draw a first portion of theharness adjacent to a second portion of the harness.

[0012] In accordance with a further aspect of the present invention, amethod of making a cardiac harness comprises providing a plurality ofmodules and connecting the modules to one another to form the harness.

[0013] In accordance with a still further aspect, the present inventionprovides a method of treating a diseased heart. A cardiac harness isprovided and is configured to fit about a patient's heart. The harnesshas a first end and a second end that are adapted to be coupled to oneanother. At least a portion of the harness is rolled about an axis. Therolled harness is placed adjacent a portion of the patient's heart, andthe harness is unrolled so that the unrolled harness fits about theheart.

[0014] In accordance with yet another aspect, the present inventionprovides a cardiac harness comprising a plurality of modules adapted tobe coupled to each other. Each of the modules comprises a plurality ofspring elements.

[0015] In accordance with still another aspect of the present invention,a cardiac harness is provided having a plurality of modules. Each modulehas a first edge, a second edge, and a zip coupling mechanism. The zipcoupling mechanism selectively draws the first and second edges adjacentto one another.

[0016] In accordance with a further aspect of the present invention, acardiac harness is provided. The cardiac harness is configured to fitabout a patient's heart, and has a base portion, an apex portion and amedial portion between the apex and base portions. The apex portion hasa plurality of spiral shaped elongate members. Each spiral shapedelongate member is connected at one end to the medial portion and at theother end to a terminal member.

[0017] In accordance with a still further aspect of the presentinvention, a cardiac harness is provided having a base portion, an apexportion and a medial portion between the apex and base portions. Thebase portion has interconnected spring elements that are oriented sothat the collective spring force around the circumference of the baseportion is in a first direction. The medial portion has interconnectedspring elements oriented so that the collective spring force around atleast a portion of the circumference of the medial portion is in asecond direction substantially different than the first direction.

[0018] In accordance with yet a further aspect, the present inventionprovides a cardiac harness having a central cavity for receiving aportion of a patient's heart so that the harness contacts the wall ofthe heart substantially throughout the cavity. The harness has aplurality of protrusions extending inwardly so that interference betweenthe protrusion and the wall of the heart aids retention of the harnesson the heart.

[0019] Further features and advantages of the present invention willbecome apparent to one of skill in the art in view of the DetailedDescription of Preferred Embodiments which follows, when consideredtogether with the attached drawings and claims.

BRIEF DESCRIPTION OF THE DRAWINGS

[0020]FIG. 1 is a schematic view of a heart with a cardiac harnessplaced thereon.

[0021]FIG. 2A-2B illustrate a spring hinge in a relaxed position andunder tension.

[0022]FIG. 3 shows an embodiment of a cardiac harness that has been cutout of a flat sheet of material.

[0023]FIG. 4 shows the cardiac harness of FIG. 3 formed into a shapeconfigured to fit about a heart.

[0024]FIG. 5 illustrates a portion of a cardiac harness having springhinges configured in accordance with one embodiment.

[0025]FIG. 6 schematically shows the portion of the harness of FIG. 5wherein a center portion of the spring hinges frictionally engages asurface of the heart.

[0026]FIG. 7 illustrates another embodiment of a cardiac harness cut outof a flat sheet of material.

[0027]FIG. 8 shows an embodiment of a cardiac harness having a windowformed therethrough.

[0028]FIG. 9 shows an embodiment of a cardiac harness having a slotformed therethrough.

[0029]FIG. 10 schematically shows an embodiment of a cardiac harness fitloosely about a heart.

[0030]FIG. 11 shows the cardiac harness of FIG. 10 being tightenedaround the heart.

[0031]FIG. 12 shows the cardiac harness of FIG. 10 tightened around theheart.

[0032]FIG. 13 shows two edge portions of an embodiment of a cardiacharness disposed adjacent one another.

[0033]FIG. 14 shows the two edge portions of FIG. 13 with a zippercoupling attached to each edge portion.

[0034]FIG. 15 shows the edge portions of FIG. 14 partially coupled toone another.

[0035]FIG. 16 shows the edge portions of FIG. 14 more fully coupled toone another.

[0036]FIG. 17 illustrates adjacent modules of a cardiac harness prior tobeing connected to one another according to one embodiment.

[0037]FIG. 18 shows the modules of FIG. 17 connected to one another.

[0038]FIG. 19 shows adjacent modules of a cardiac harness configured tobe connected to one another according to another embodiment.

[0039]FIG. 19a schematically shows an end view of edges of the modulesof FIG. 19 aligned with each other and showing a zip coupler.

[0040]FIG. 20 shows the modules of FIG. 19 connected to one another.

[0041]FIG. 21 shows an embodiment of a ribbon-shaped harness connectedto deployment rods.

[0042]FIG. 22 shows the harness of FIG. 21 wrapped around a heart.

[0043]FIG. 23 shows the harness of FIG. 21 wrapped in a scroll mannerabout the deployment rods.

[0044]FIG. 24 shows the harness of FIG. 21 partially deployed on aheart.

[0045]FIG. 25 shows an embodiment of a ribbon-type harness with thefirst and second edges of the harness about to be joined together.

[0046]FIG. 26 shows a side view of a delivery apparatus for aribbon-type harness.

[0047]FIG. 27 illustrates another view of the delivery apparatus of FIG.26.

[0048]FIG. 28 shows a close-up view of a portion of the deliveryapparatus of FIG. 26.

DETAILED DESCRIPTION OF PREFERRED EMBODIMENTS

[0049]FIG. 1 illustrates a mammalian heart 30 with a cardiac harness 32applied thereto. The illustrated cardiac harness 32 comprises a seriesof hinges or spring elements that circumvent the heart and,collectively, apply a mild compressive force on the heart so as toalleviate wall stresses. As discussed in Applicant's co-pendingapplication entitled “Expandable Cardiac Harness For Treating CongestiveHeart Failure,” Ser. No. 09/634,043, which was filed on Aug. 8, 2000,the entirety of which is hereby expressly incorporated by reference,remodeling of a diseased heart can be resisted or even reversed byalleviating the wall stresses in such a heart.

[0050] The term “cardiac harness” as used herein is a broad term thatrefers to a device fit onto a patient's heart to apply a compressiveforce on the heart during at least a portion of the cardiac cycle. Otherdevices that are intended to be fit onto a heart and are referred to inthe art as “girdles,” “socks,” “jackets,” or the like are includedwithin the meaning of “cardiac harness.”

[0051] The cardiac harness 32 illustrated in FIG. 1 comprises at leastone undulating strand 34 comprising a series of spring elements 36referred to as hinges or spring hinges that are configured to deform asthe heart 30 expands during filling. Each hinge 36 providessubstantially unidirectional elasticity, in that it acts in onedirection and does not provide much elasticity in the directionperpendicular to that direction. FIG. 2A shows one embodiment of a hingemember 36 at rest. The hinge member 36 has a central portion 40 and apair of arms 42. As the arms 42 are pulled, as shown in FIG. 2B, abending moment 44 is imposed on the central portion 40. Thus, there is aforce resisting deformation. A typical strand 34 of hinges 36 comprisesa series of such hinges 36, which are adapted to elastically expand andretract in the direction of the strand 34.

[0052]FIGS. 3 and 4 illustrate an embodiment of a cardiac harness 50,shown at two points during manufacture of the harness. In theillustrated embodiment, the harness 50 has been etched from a thin sheetof Nitinol, which is a superelastic material that also exhibits shapememory properties. The flat sheet of material is draped over a form, dieor the like so that it takes on the shape of at least a portion of aheart (see FIG. 4).

[0053] With continued reference to FIGS. 3 and 4, the harness 50comprises a base portion 52, which is sized and configured to generallyengage and fit onto a base region of the heart 30; an apex portion 54,which is sized and shaped to generally engage and fit on an apex regionof the heart; and a medial portion 56 between the base and apex portions52, 54.

[0054] As shown in FIGS. 3 and 4, the harness 50 comprises severalstrands 34 or rows of undulating wire comprising spring hinges 36. Thestrands of spring hinges in the illustrated embodiment are oriented indifferent directions and are configured differently in the variousportions of the harness. For example, in the base portion 52 of theharness 50, strands 58 are oriented so that the spring elements 59 willexpand and contract in a direction generally transverse to alongitudinal axis Lc of the heart 30. As such, a collective spring forcearound the circumference of the base portion 52 is directed generallytransverse to the longitudinal axis Lc.

[0055] In the medial portion 56, strands 60 are oriented so that springelements 61 expand and contract in a generally longitudinal direction.Additionally, several of the longitudinally-extending strands 60 areconnected to one another by interconnecting spring elements 62, whichconnect the strands 60 but still allow relative movement therebetween.However, some longitudinal strands 60 are not connected to adjacentlongitudinal strands 60; these unconnected longitudinal strands can movefreely relative to one another in the transverse direction. As shown,the medial portion 56 includes a combination of spring directions. Ofcourse, the longitudinally-directed springs 61 exert a spring force inthe longitudinal direction, and the transversely-directed springs 62exert a spring force in the transverse direction. Collectively, however,the spring hinges 61, 62 in the medial portion 56 exert a spring forcearound the circumference of the harness 50 that is directed in a medialdirection between the longitudinal and transverse directions.

[0056] In the apex portion 54, an “archimedes spiral” 64 configurationof the harness allows compliant expansion and deformation of the harnessin more than one direction. The archimedes spiral 64 comprises aplurality of spiral shaped elongate members 66 disposed adjacent oneanother. A first end 68 of each of the elongate members 66 is connectedto the medial portion 56. In the illustrated embodiment, the elongatemember 66 is coextensive with a longitudinally-oriented spring hinge 61.A second end 69 of each elongate member 66 is connected to a terminalmember 70. As such, a plurality of spiral shaped elongate members 66 areconnected to a terminal member 70. The illustrated archimedes spiral 64in the apex portion 54 has relatively high compliance, and is mostcompliant in a longitudinal direction.

[0057] In a mammalian heart, the heart muscle cells in the base regiontend to expand and contract in a generally transverse direction duringpumping of the heart. In the apex region, the heart muscles tend toexpand and contract in a generally longitudinal direction. Between theapex and base regions of the heart, the heart muscles generally expandin directions between the longitudinal and transverse directions. Assuch, the arrangement of spring hinges in the base, medial and apexportions 52, 56, 54 of the harness 50 illustrated in FIGS. 3 and 4 isspecially adapted to accommodate the natural expansion and contractionof heart muscle. The spring elements 59, 61 in each portion are orientedgenerally in the directions of the pericardial muscle expansion in thecorresponding region of the heart so as to more precisely resistexcessive expansion of the heart. Accordingly, the harness 50 helps todecrease the workload of the heart 30, enabling the heart to moreeffectively pump blood through the patient's body. Decreasing itsworkload also gives the heart an opportunity to heal itself.

[0058] With continued reference to FIGS. 3 and 4, the strands 58 ofspring elements 59 in the base portion 52 are connected one to anotherby interconnecting elements 72. In this manner, when the rows/strands 58expand and contract in a transverse direction, the interconnectingelements 72 prevent the harness 50 from growing smaller in alongitudinal direction, or foreshortening. This provides an importantbenefit, because foreshortening of the harness 50 in the base portion 52could create a force that squeezes the heart longitudinally. Of course,this could make the heart smaller in a longitudinal direction, even asthe heart expands circumferentially. This could increase the sphericityof the heart to a degree that is undesired and may be inefficient forpumping. By eliminating or resisting foreshortening, the present harnesshelps to maintain the natural shape of the heart and/or limits thesphericity of the heart.

[0059] In another embodiment, the interconnecting elements comprisecompliant springs. Such compliant interconnecting elements help maintainthe relative positions of the strands but allow for longitudinalexpansion and contraction of the heart with little or no resistance bythe harness. Thus, compliant interconnecting elements also help theharness avoid foreshortening.

[0060] As discussed above, the cardiac harness embodiment illustrated inFIGS. 3 and 4 is etched out of a flat sheet of Nitinol. After formingthe flat sheet into a desired shape as shown in FIG. 4, the Nitinolmaterial preferably is annealed by being placed in an oven at about 475°C. for about 20 minutes. The harness 50 then is removed from the ovenand quenched in cold water. The harness retains or “memorizes” theannealed shape. Due to the shape memory properties of Nitinol, theharness can then be deformed, even plastically deformed, at certaintemperatures, but when the deformed harness is returned to a shapememory temperature range, the harness will resume its annealed shape.This can be especially helpful in embodiments wherein the harness isdelivered via minimally-invasive surgical methods. In such embodiments,the harness is compressed and/or folded so as to be more easilyintroduced into the body, but expands to its memory shape when exposedto the body's warm internal temperatures.

[0061] Although the embodiments of FIGS. 1-4 are constructed of Nitinol,it is to be understood that various designs and materials can be usedfor a cardiac harness. For example, suitable materials include metalsand polymers such as, for example, Nitinol, other shape memory materialsincluding metal alloys or polymers such as oligo (e-caprolactone)dimethacrylate, stainless steel, Elgiloy™, titanium, tantalum,polyimide, polyethylene, nylon, polypropylene, polycarbonate, ePTFE andpolyester.

[0062] In the embodiment illustrated in FIGS. 3-4, a flat sheet ofNitinol has been photochemically etched and then bent into a desiredshape. It is to be understood that any of a variety of methods ofmanufacture can be used to create a sheet that can later be formed intoa harness, or even to directly create a harness that generallycomplements the shape of a heart without having to be deformed. Suchmanufacturing processes can include, for example, casting, mechanicalmachining, cutting with a waterjet, EDM, milling, laser cutting, andstamping. After the harness has been created, the harness preferably ispolished by an electrochemical or a mechanical method.

[0063] One aspect of the cardiac harness 50 shown in FIGS. 3 and 4 isthat by etching the harness as a single unitary structure, there are nooverlapping wires or filaments, and no connections, such as welds, areneeded. As such, the spring hinges operate without overlapping andcontacting the other spring hinges. Thus, wear incident to frictioncreated by such overlapping materials is avoided. Also, stressconcentrations that could result from welds and other mechanicalconnections are avoided.

[0064] In another embodiment, drawn wire can be formed into undulatingstrands of spring hinges that collectively form a cardiac harness. Acardiac harness 32 formed of drawn wire can be configured so thatadjacent rows 34 of spring hinges 32 overlap and are interwoven with oneanother as shown in the embodiment of FIG. 1. In other embodiments, thecardiac harness is configured so that the rows of spring hinges made ofdrawn wire do not overlap or contact adjacent spring hinges. Preferably,the wire comprises drawn Nitinol wire that is annealed so as to“remember” its undulating shape.

[0065] Embodiments of cardiac harnesses can be provided in varioussizes, shapes and configurations. As discussed above, the harness 50embodiment illustrated in FIGS. 3 and 4 comprises a generally circularsheet that is deformed into a generally conical shape to accommodate apatient's heart. In another embodiment, the harness is not quitecircular when in sheet form, so that when the sheet is deformed into agenerally conical shape, a distance from base to apex is longer on oneside of the harness than on another. In still other embodiments, theheart can comprise a ribbon or fan comprising a series of adjacentundulating rows of spring hinges.

[0066] The compliance of a cardiac harness can be custom-tailored asdesired during manufacture by using special configurations of the springelements. Not every spring element in the harness need have the samecompliance characteristics. For example, some spring elements may havelonger arms than other spring elements. The longer-armed hinges likelywill be more compliant than the shorter-armed hinges. Another way tovary compliance for different areas of the harness is for some springelements to be thicker than others. The thicker springs will resistdeformation with a greater force. Depending upon placement of the springelements, one portion or area of the harness can be more compliant thanother areas of the harness.

[0067] In one embodiment, a first set of springs deform readily uponapplication of a first threshold force, and a second set of springsbegin to deform only when a second force threshold has been reached.Thus, the cardiac harness exhibits a compliance curve that is verycompliant over a first range of strain but becomes dramatically stifferupon reaching a chosen threshold of strain. This can be helpful if it isdesired to exert more compressive force on a larger heart than on asmaller, possibly-less-diseased heart.

[0068] With continued reference to FIGS. 3 and 4, an anchoring mechanismcan be included in the harness 50. The anchoring mechanism helps retainthe harness in position on the heart 30. As discussed above, the harness50 is configured to be fit about a portion of the patient's heart. Theportion of the heart fits within a central cavity 74 of the harness 50.In the illustrated embodiment, the outermost row 76 of undulationsincludes a series of barbs 78 extending from some of the spring elements59. The barbs 78 can be bent inwardly so that they extend into thecentral cavity 74 of the harness 50. When the harness 50 is placed upona heart, each barb 78 at least partially engages or pierces the heartwall, thus resisting movement of the harness downwardly toward the apexof the heart and off of the heart muscle. In the illustrated embodimentthe barbs 78 are integrally formed with the harness 50 as it is etched.

[0069] Another embodiment of an anchoring apparatus is represented inFIGS. 5 and 6. FIG. 5 shows a portion of a cardiac harness 80 whichincludes rows 82 of spring hinges 84. Each spring hinge 84 has a bottomcenter portion 86, which can be bent inwardly so as to protrude into thecentral cavity of the harness 80. As shown schematically in FIG. 6, whenthe harness 80 is placed against the patient's heart 30, the inwardlybent bottom center portions 86 engage the epicardium of the heart 30.Although the center portions 86 of the hinge 84 are not sharp and do notpenetrate cardiac tissue like the barbs, their engagement with the heartwall creates significant resistance so that the interference generatedby many bottom center portions 86 working together resists movement ofthe harness 80 toward the apex and off of the heart.

[0070] In a still further embodiment, a portion of the harness can beconfigured to protrude into the central cavity by providing one or morespring hinges that are stiffer than surrounding spring hinges. Sincesuch stiffer spring hinges will not be as compliant as the surroundingharness, they will have more of a tendency to protrude into the centralcavity and thus provide additional interference between the harness andthe wall of the heart.

[0071]FIG. 7 shows another embodiment of an etched unitarily-formedcardiac harness 90 prior to being formed into a desired shape. As can beseen in the figure, the illustrated embodiment comprises a differentarrangement and configuration of spring elements 92 than is found inFIGS. 1 or 3. Adjacent rows 94 of spring elements 92 are connected bysubstantially straight interconnecting elements 96, which extend fromthe base 98 to the apex 100 and bend into an archimedes spiral 102arrangement in the apex portion 100 of the device. FIGS. 8 and 9 eachillustrate embodiments wherein the harness 90 of FIG. 7 is molded into aform adapted to engage a heart.

[0072] As discussed above, various configurations of spring elements 92can advantageously be used in a cardiac harness. Such configurations mayinclude several rows 94 of spring elements 92 that may or may not beinterconnected together by connecting elements 96. Further, suchconnecting elements may also include spring elements or even an elasticmaterial so that the adjacent rows of spring hinges are moveablerelative to one another.

[0073]FIGS. 8 and 9 each illustrate embodiments wherein a portion of aharness 90 has been removed. In FIG. 8, a window 104 is formed through aside of the harness, but the outermost strand 106 of the harness in thebase remains undisturbed. In FIG. 9, the outermost strand of the harnesshas also been interrupted. Thus, a slot 108 is formed through a side ofthe harness, and the outermost strand 106 no longer completelycircumvents the heart. The window 104 and slot 106 embodiments provideaccess for a surgeon to perform certain surgical procedures, such as,for example, cardiac bypass, or installing and working with coronaryartery grafts. In some embodiments, it may be preferable to reattachportions of the harness that have been removed so as to regain theelasticity and support that was removed with the window or slotportions.

[0074] Installation Methods and Apparatus

[0075] Any suitable method can be employed to install a cardiac harnesson a patient's heart. For example, the harness can be slid over theheart during an open thoracic surgery procedure or during a surgeryusing minimally-invasive methods. However, hearts, especially beatinghearts, are slippery and can be difficult to work with. Additionally, inorder for the harness to apply a compressive force on the heart wheninstalled, the harness preferably is somewhat smaller than the patient'sheart when the spring hinges are at rest. As the harness is drawn overthe heart during installation, the harness squeezes the heart, and theheart may tend to slide away from the harness, making it difficult toinstall the harness onto the heart.

[0076] In accordance with another embodiment, a cardiac harness can beinstalled on the heart without having to slide an intact harness overthe heart. Instead, a harness such as that shown in FIGS. 4, 8 and 9 ismodified so as to be split or cut longitudinally along at least aportion of the length of the harness from the base to the apex. As such,the harness can be fit loosely adjacent and around the heart withoutsqueezing the heart during installation. Once placed adjacent the heart,the harness can be wrapped about the heart to restore thecircumferential continuity of the harness. The edges of the harness atthe longitudinal split can be reattached in any known manner, such as bysutures, clips, hooks or by a zip coupler as discussed below.

[0077] With reference next to FIGS. 10-12, another embodiment of acardiac harness 110 comprises opposing first and second longitudinaledges 112, 114. When the first and second longitudinal edges 112, 114are aligned with one another, the harness 110 is substantiallycircumferentially continuous and is shaped to fit about a heart. Aclosure device 116 is attached along the first and second edges 112,114. In the illustrated embodiment, the closure device 116 comprises azip coupler 118 in the form of a zipper 119. Mating components 120comprising zipper teeth 122 are disposed on a fabric backing 124 that isattached to the corresponding harness edge by sutures.

[0078] FIGS. 10-12 illustrate the harness 110 being installed over apatient's heart 30. To install the harness, the zipper 119 is disengagedand the harness 110 is fitted loosely about the heart 30 as shown inFIG. 10. The harness 110 does not fit circumferentially all the wayaround the heart when the spring hinges 125 are at rest. As a zipperactuator 126 or coupling member is advanced longitudinally along themating components 120, as shown progressively in FIGS. 11 and 12, themating components 120 interlock with one another so that the harness 110is closed about the heart 30. The first and second edges 112, 114 of thecardiac harness 110 are drawn toward each other and held in position. Inthis manner, it is easy and effective to close the harness over theheart so as to circumferentially surround the heart, even though aresting size of the harness is smaller than the heart.

[0079] The actuator or coupling member 126 can be advanced by hand orcan be held with a tool to advance it along the length of the matingcomponents 120. Once interlocked, the mating teeth 122 providecircumferential strength for the harness 110 and also provide somelongitudinal strength. When the harness is closed, the zip coupler 118is interposed between the harness edges 112, 114, and the edges may thusbe spaced from each other. However, circumferential forces in theharness 110 are communicated to spring hinges 125 adjacent the edges112, 114 through the zip coupler 118.

[0080] It is to be understood that variations and embodiments of a zipcoupler can be advantageously employed in the present invention. Forexample, any of a variety of zip coupling mechanisms can be used toobtain an effect similar to the illustrated zipper, which effect is thatopposing edges are drawn transversely toward each other as an actuatormember is moved longitudinally along the edges. Other exemplary zipcoupling mechanisms include “zip-lock” type mechanisms in which a firstelongate mating component having a male member engages a second elongatemating component having a female member.

[0081] In the illustrated embodiment, the coupling member 126selectively locks or unlocks the mating components 120. Thus, if thecoupling member 126 is advanced to close the harness 110 about the heart30, but the clinician is not satisfied with the fit or positioning ofthe device, the coupling member 126 can be retracted so as to unlock themating components and loosen the harness. This enables the clinician toeasily adjust and resecure the device on the patient's heart.

[0082] After the mating components 120 have been locked together, thecoupling member 126 can be left in place or can be completely removedfrom the zip coupling mechanism 118. The mating components 120 willremain interlocked after the coupling member 126 is removed. However,with a conventional zipper, when the coupling member has been removed,there is a chance that the mating components will unlock from each otherif the ends of the components are not held together. To counteract thispossibility, a secondary coupling 128 is provided to hold the matingcomponents 120 in an interlocked position at two or more locations alongtheir length. The secondary coupling 128 prevents the mating componentsfrom working apart from each other.

[0083] Secondary coupling members can comprise clips, sutures or thelike. In another embodiment, the secondary coupling members comprise apair of relatively small and biologically inert magnets arranged to holdthe mating components together. The magnets preferably comprise rareearth magnets made of neodymium, iron and/or boron and are availablefrom Jobmaster Magnets. In one embodiment, the magnets are attached tothe edges of the cardiac harness or to the mating components by anepoxy, and are arranged to automatically engage one another when theharness is closed. As such, no additional steps are required to apply asecondary coupling.

[0084] The mating components 120 and coupling member 126 can be formedof any material, such as metals or polymers. As discussed above, themating components 120 may be attached to a fabric backing 124, which inturn is attached to the corresponding harness edge 112, 114. However, itis to be understood that the elongate mating components can also beattached directly to the harness, or can even be co-formed therewith.

[0085] FIGS. 13-16 illustrate an embodiment in which elongate matingcomponents are attached directly to edges of a cardiac harness. Withspecific reference to FIG. 13, a portion of an etched cardiac harness130 is shown. The etched harness 130 includes a first longitudinal edge132 and a second longitudinal edge 134. Each edge 132, 134 connects toseveral rows 136 of interconnected springs 138. A series of small holes140 are provided along each longitudinal edge 132, 134. As shownspecifically in FIG. 14, an elongate mating component 142 is attachedalong each edge. In the illustrated embodiment, the mating components142 comprise zipper teeth 144 that are attached to the edges 132, 134 bysutures, adhesives or like which extend through the holes 140. FIGS. 15and 16 show an actuator or coupling member 146 being advanced along themating components 142 so as to draw the adjacent edges 132, 134 togetherin an interlocked fashion.

[0086] In the illustrated embodiment, a zip coupling mechanism is usedin conjunction with a cardiac harness 130 having spring hinges 138. Itis to be understood, however, that a zip coupling mechanism can be usedwith any type of cardiac harness. For example, a cardiac harnessconstructed of an elastic or nonelastic woven or knit fabric, polyestermesh or other material can include a zip coupling mechanism. Such aharness can have first and second edges having elongate matingcomponents that can be coupled together by a coupler member in a manneras discussed above.

[0087] The mating components can be attached directly to the first andsecond edges, or can be mounted on a fabric backing which is attached tothe edges. In some embodiments, the fabric backing comprises a compliantor elastic material. As such, even if the harness is relativelyinelastic, the elastic fabric backing of the zip coupler provides somecompliance. As such, there is less of a chance that the harness will betoo tight when installed on the heart.

[0088] An important step in using a zip coupling apparatus is engagingthe coupling member 126, 146 with both of the elongate mating members120, 142 so that the mating members will interlock appropriately witheach other as the coupling member is advanced. In an additionalembodiment, a harness has a zip coupling mechanism having elongatemating members that are substantially longer than the harness so thatbeating of the heart does not substantially disturb a connection end ofthe mating members at which the coupling member is installed. In a stillfurther embodiment, the mating members extend out of a patient's bodycavity when the harness is placed adjacent to the heart and is ready tobe finally coupled thereto. In this manner, the clinician can engage thecoupling member with both elongate mating components at a positionoutside of the patient's body. Such engagement thus is comparativelyeasy. The clinician then advances the coupling member so as to close theharness about the heart. In another embodiment, the coupling member isalready engaged with the elongate mating components when the harness isadvanced into the patient's body cavity.

[0089] Once the coupling member is engaged, it can be advanced along theelongate mating components until the mating components are lockedtogether. The coupling member can continue to be advanced until itextends off of the mating components, and the coupling member can thenbe removed from the patient's body. The elongate mating components canthen be trimmed so that they extend along the harness edges and haverelatively little surplus length. As discussed above, magnets or othersecondary coupling members can be provided to prevent the matingcomponents from unraveling.

[0090] Modular Construction

[0091] In accordance with another embodiment, a cardiac harness includesa plurality of individual components or modules that are assembledtogether to form a cardiac harness. The modules can include zipcouplings so that assembly of the harness comprises using the zipcouplings to engage adjacent modules with each other. Other methods andapparatus for coupling adjacent modules, such as applying clips, glue orthe like, can also be used. Still further, edges of at least some of themodules can be manufactured so as to engage opposing edges of adjacentmodules through hooks, compression fittings or the like.

[0092] With reference next to FIGS. 17 and 18, modules 150 of anembodiment of a cardiac harness are shown. Each of the modules 150 hasan elongate mating member 152 comprising zipper teeth 154 attached to anedge 156 of the corresponding module 150. The mating members 152 arecoupled together in a manner as discussed above. As shown in FIG. 18,multiple modules 150 are joined to one another by engaging the matingmembers 152. Successive modules 150 can be added until a full cardiacharness is formed.

[0093]FIGS. 19, 19a and 20 show another embodiment of cardiac harnessmodules 160 comprising a zip coupler 162 in the form of a “zip lock”fastener which comprises a male member 164 adapted to engage a femalemember 166. The male member 164 is mounted along an edge 168 of a firstmodule 170 and the female member 166 is aligned along an edge 172 of asecond module 174. When the male and female members 164, 166 areengaged, the modules 170, 174 are held together as shown in FIG. 20. Inthe embodiments illustrated in FIGS. 17-20, the respective zip couplers162 are interposed between adjacent modules 170, 174, and the moduleedges 168, 172 do not actually contact one another.

[0094] It is to be understood that several types of fasteners orcoupling mechanisms can be used to couple adjacent modules. Thesemechanisms include releasable mechanisms such as the zip couplingmechanisms shown in FIGS. 17-20 and also include permanent couplingmechanisms. For example, in another embodiment, adjacent modules 150,160 are connected to one another by applying a layer of silicone on andbetween the modules. Various polymers can also be used to permanentlybond or couple adjacent modules to one another.

[0095] Assembly of cardiac harness modules can be accomplished ex vivoand/or in vivo. In vivo assembly can be performed as part of aminimally-invasive surgical delivery of the device. Modular constructionof the harness is advantageous for minimally-invasive procedures becausethe profile of each module is smaller than the profile of the assembledharness. A smaller delivery opening and passage to the heart can be usedif the harness is advanced module by module than if the harness isadvanced fully assembled. Multiple zip couplings can be used to assemblethe harness in vivo.

[0096] A modular harness allows for precise customization of the harnessto a particular patient's heart size and needs. Compliance and placementof spring elements can be specially adapted for a patient's heart. Forexample, certain modules having a greater collective spring constant maybe joined with modules having greater flexibility so that the stifferspring elements are disposed around the patient's left ventricle, whilethe more compliant spring elements are provided around the rest of thepatient's heart. Still further, some modules may include spring hingeswhile others do not.

[0097] A modular approach also allows a cardiac harness manufacturer toaccommodate a broad range of heart shapes and sizes while maintaining arelatively low inventory of module sizes. This is because a limitednumber of modules of different sizes and compliance can be mixed andmatched to construct cardiac harnesses having a broad range of sizes andcompliance as required by patients.

[0098] The modules 150, 160 can be formed in various sizes and shapes.For example, the modules can comprise longitudinal strips,circumferential strips, spiral strips, or the like.

[0099] Scrolled Harness

[0100] With reference next to FIGS. 21-24, another embodiment of acardiac harness 180 and a method for installing the harness is providedand illustrated. With specific reference to FIG. 16, the illustratedcardiac harness 180 comprises a plurality of rows 182 of undulationscomprising spring hinges 184. As can be seen in the figure, theconstruction shares many similarities with other embodiments such asthose described in FIGS. 3 and 7; however, the illustrated harness 180is generally ribbon- or fan-shaped and has first and second ends 186,188. In the illustrated embodiment, the ribbon-shaped harness 180 isgenerally rectangular. In other embodiments, the ribbon-shaped harness180 can be generally arcuate.

[0101] As with previously discussed harness embodiments, theribbon-shaped harness 180 preferably is formed of a flexible material.In the illustrated embodiment, the ribbon-shaped harness is etched froma flat sheet of Nitinol. In other embodiments, other materials, such asdrawn Nitinol wire, can be used to formed a ribbon-shaped harness.Additionally, such a harness could be constructed out of flexible,non-metal and non-superelastic materials.

[0102] A deployment apparatus 190 comprises first and second deploymentrods 192, 194 which are depicted in FIG. 21. The first and second ends186, 188 of the cardiac harness 180 are connected to the deployment rods192, 194. The substantially flat, fan-shaped configuration of theharness 180 allows a clinician to place the harness adjacent the heart30 and, using the rods 192, 194, to easily and quickly wrap the harness180 around the heart 30 (See FIG. 22), even when the heart is beating.This construction and mode of deployment allows the harness to beinstalled without having to be slid longitudinally over the heartepicardium. Trauma to the epicardium is minimized or avoided.

[0103] With reference next to FIG. 23, the harness 180 preferably iswrapped about the deployment rods 192, 194 in a scroll-typeconfiguration prior to deployment onto the heart. The scroll-typeconfiguration has a very low profile and can be inserted into apatient's body cavity using minimally-invasive surgical methods.

[0104] To install the harness 180 on the patient's heart 30, theclinician positions the rods 192, 194 having the harness scrolledthereupon immediately adjacent the heart's epicardium, and then movesthe rods 192, 194 around opposing sides of the heart while rotating therods. As the rods move about the heart, the harness 180 unscrolls fromthe rods and onto the heart epicardium, as illustrated in FIGS. 22 and24. Once the harness 180 completely encircles the heart, as shown inFIG. 22, the first and second ends 186, 188 of the harness 180 areengaged with one another. The ends are then released from the rods 192,194 and the rods are removed. The harness 180 is left in place on thepatient's heart 30.

[0105] Any suitable apparatus or method can be used to engage the endswith one another and/or to releasably hold the ends to the deploymentrods. For example, clips, sutures, surgical adhesives, magnets,biodegradable materials, etc. can suitably be used.

[0106] With next reference to FIG. 25, one embodiment of a ribbon-typeharness 180 employs a zip coupling mechanism 200 to aid closure of theharness. Connecting members 202 extending from the ends of the harness180 connect the harness to the rods 192, 194. In the illustratedembodiment, the connecting members 202 comprise suture material.Elongate mating members 204 are provided along the first and second ends186, 188 of the fan-shaped cardiac harness 180. The elongate matingmembers 204 extend far beyond the ends 186, 188 so as to extend out ofthe patient's body cavity during surgery. Preferably, a portion of themating members 204 is connected directly to the ends 186, 188 and afabric backing 206 or the like is provided to support the mating members204 proximal of the harness ends.

[0107] Once the harness 180 is placed around the heart 30 as depicted inFIGS. 22 and 25, the clinician advances a coupling member 208 of the zipcoupling mechanism 200 along the elongate mating members 204 into thebody cavity and along the harness. As the coupling member 208 movesalong the mating members 204 on the harness 180, the connecting members202 are detached from the deployment rods 192, 194, and the rods aremoved out of the way. The coupling member 208 draws the first and secondends 186, 188 of the harness matingly adjacent each other, thus holdingthe harness 180 in place on the patient's heart 30. Once the couplingmember 208 has been fully extended, extra and unnecessary portions ofthe mating members 204 are trimmed away and one or more secondaryconnector members can be attached to prevent the interlocked matingmembers from unraveling.

[0108] It is to be understood that a variety of methods and apparatusfor joining the opposing edges of the harness can be employed. Forexample, magnets, sutures, clips, medical adhesives and the like can beused to join the ends

[0109] In one embodiment, a Nitinol ribbon-type harness is formed to fita patient's heart size and shape and then is annealed in that positionso that it will “remember” the shape. The harness will assume theannealed shape within a patient's body even though the harness may bedeformed when scrolled upon the rods. In another embodiment, the Nitinolharness is first scrolled about the rods and then annealed in thescrolled configuration. For both of these embodiments, once the harnessis deployed around the patient's heart, it exerts an inwardly-directedcompressive force on the heart, which force will alleviate wall stressduring diastolic filling of the heart.

[0110] With reference next to FIGS. 26-28, a scroll harness deliveryapparatus 210 is shown. The scroll harness delivery apparatus 210includes first and second deployment rods 192, 194 that are adapted tohold the harness 180 in the scrolled configuration. The harness isattached to a holding portion 212 of each rod 192, 194 which ispositioned adjacent a distal end of the corresponding rod. A bendingportion 214 is provided on each rod 192, 194 proximal of the holdingportion 212. As such, the rods are configured so that as they rotate inopposite directions relative to one another, the holding portions 212 ofthe adjacent rods 192, 194 move from being immediately next to oneanother (see FIG. 26) to being spaced apart (see FIG. 27). Upon stillfurther rotation, the holders 212 again become disposed immediately nextto one another.

[0111] A proximal end of the deployment rods 192, 194 is supported by ahandle 216. An actuator rod 218 extends proximally from the handle 216.The actuator rod 218 rotates with the first deployment rod 192. Withspecific reference to FIG. 28, a gear 220 on the second deployment rod194 engages a gear 222 on the actuator rod 218 so that when the actuatorrod 218 is rotated in a first direction, and the first deployment rod192 correspondingly rotates in that first direction, the seconddeployment rod 194 is rotated in the opposite direction.

[0112]FIG. 26 shows the apparatus 210 in a loading state in which theholding portions 212 of the deployment rods 192, 194 are positionedgenerally adjacent one another so that the harness 180 can be tightlywound thereupon like a scroll, as shown in FIG. 23. As the actuator rod218 is rotated, the deployment arms 192, 194 move to an open position inwhich the holding portions 212 are spaced from each other, as shown inFIGS. 27 and 24. Continued rotation of the actuator continues therotation of the deployment arms 192, 194, which eventually meet eachother again as shown in FIG. 22. -At this point the scroll harness hasbeen deployed around the patient's heart 30 and needs only to be securedin place.

[0113] Sizing The Cardiac Harness

[0114] One consideration when applying a cardiac harness to a patient'sheart in order to resist remodeling and promote reverse remodeling ofthe heart is to obtain a correctly sized cardiac harness to apply to thepatient's heart. It is important to achieve a proper tension of theharness in order to apply an appropriate inwardly-directed compressiveforce so as to reduce wall stresses in the heart. If too much tension isprovided, the heart could be constricted. If too little tension isprovided, the device will provide reduced or no benefit for the patient.

[0115] Existing fabric harnesses, such as the Acorn™ Cardiac SupportDevice (CSD), require a surgeon to first loosely install the device overthe patient's heart, and then manually tension the device while thedevice is in place. There is no algorithm or direction for the surgeonto determine and obtain the proper tension. This allows a potential foroperator error and also allows for inconsistency between patients andsurgeons.

[0116] Accordingly, it is desired to pre-size a cardiac harness to apatient's heart before installing the harness on the heart. Also, it isdesired to have the pre-sizing procedure be as minimally invasive aspossible for the patient.

[0117] Imaging data can be obtained non-invasively before any harnessinstallation surgery is performed. Imaging such as echocardiography, CTScanning, MRI Scanning, and ventriculography can be used. Other types ofimaging can also be useful. It is anticipated that measuring thediameter of the heart, the volume of the heart, and the cross-sectionalarea of the heart at the end of diastole and at the end of systole willenable a clinician to determine a desired size of the heart and thus todesign or prescribe a desired harness size and configuration.

[0118] Once a desired harness size and configuration is determined, theharness can be made from modular components in a manufacturer's orclinician's stock or can be custom fabricated for each patient. Aparticular harness size and/or configuration can be suitable for a rangeof heart sizes.

[0119] A harness can be chosen or made so that it applies apredetermined maximum epicardial pressure to the heart at the end ofdiastole. Preferably, the applied pressure at the end of diastole isgreater than about 2 mm Hg but less than about 10 mm Hg, and morepreferably is between about 4-8 mm Hg. Preferably, pressure is appliedthroughout the cardiac cycle and is greatest at the end of diastole.

[0120] In accordance with another embodiment, a cardiac harness isconfigured to be expandable beyond the end diastolic dimension to whichit is sized in case the heart expands acutely. In this manner, pressureis applied to the epicardial surface at end diastole, but an enddiastolic dimensional limit is not imposed on the heart.

[0121] Although this invention has been disclosed in the context ofcertain preferred embodiments and examples, it will be understood bythose skilled in the art that the present invention extends beyond thespecifically disclosed embodiments to other alternative embodimentsand/or uses of the invention and obvious modifications and equivalentsthereof. In addition, while a number of variations of the invention havebeen shown and described in detail, other modifications, which arewithin the scope of this invention, will be readily apparent to those ofskill in the art based upon this disclosure. It is also contemplatedthat various combinations or subcombinations of the specific featuresand aspects of the embodiments may be made and still fall within thescope of the invention. Accordingly, it should be understood thatvarious features and aspects of the disclosed embodiments can becombined with or substituted for one another in order to form varyingmodes of the disclosed invention. Thus, it is intended that the scope ofthe present invention herein disclosed should not be limited by theparticular disclosed embodiments described above, but should bedetermined only by a fair reading of the claims that follow.

What is claimed is:
 1. A cardiac harness configured to fit about apatient's heart, comprising a plurality of individual modules assembledtogether to form the harness.
 2. The cardiac harness of claim 1, whereinone of the modules is more compliant than another of the modules.
 3. Thecardiac harness of claim 1, wherein at least two adjacent modules areselectively releaseable from one another.
 4. The cardiac harness ofclaim 3, wherein at least two adjacent modules are connected to eachother.
 5. The cardiac harness of claim 4, wherein the zip couplingcomprises a zipper.
 6. The cardiac harness of claim 4, wherein the zipcoupling comprising an elongate male member that is selectively engagedwith an elongate female member.
 7. The cardiac harness of claim 1,wherein at least one pair of adjacent modules are permanently affixed toone another.
 8. The cardiac harness of claim 7, wherein at least onepair of adjacent modules are connected by silicone.
 9. The cardiacharness of claim 1, wherein at least one of the modules comprises aspring hinge.
 10. A cardiac harness configured to fit about a patient'sheart, comprising: a first module which extends along a first portion ofa circumference of the harness; and a second module which extends alonga second portion of the circumference of the harness; wherein the firstand second modules are connected to one another.
 11. The cardiac harnessof claim 10, wherein the first and second modules are connected to oneanother by a coupling mechanism interposed between the modules.
 12. Thecardiac harness of claim 11, wherein the coupling mechanism comprises azip coupling mechanism.
 13. The cardiac harness of claim 11, wherein thecoupling mechanism comprises silicone.
 14. A cardiac harness configuredto fit about a patient's heart, comprising a zip coupler configured toselectively draw a first portion of the harness adjacent a secondportion of the harness.
 15. The cardiac harness of claim 14 additionallycomprising a secondary coupler adapted to hold the first portion of theharness adjacent the second portion.
 16. The cardiac harness of claim15, wherein the secondary coupler comprises a magnet.
 17. A method ofmaking a cardiac harness, comprising: providing a plurality of modules;and connecting the modules to one another to form the harness.
 18. Themethod of claim 17, wherein a connecting member is disposed between eachmodule.
 19. The method of claim 18, wherein the connecting membercomprises a zip coupler.
 20. The method of claim 18, wherein theconnecting member comprises silicone.
 21. A method of treating adiseased heart, comprising providing a cardiac harness configured to fitabout a patient's heart and comprising a first end and a second end thatare adapted to be coupled to one another; rolling at least a portion ofthe cardiac harness about an axis; placing the rolled cardiac harnessadjacent a portion of the patient's heart; and unrolling the harness sothat the unrolled harness fits about the heart.
 22. The method of claim21 additionally comprising connecting the first and second ends to eachother after the harness has been unrolled about the heart.
 23. A methodof deploying a cardiac harness about a patient's heart, comprising:providing a cardiac harness configured to fit about a patient's heartand comprising a first end and a second end that are adapted to becoupled to one another; providing a deployment apparatus comprising adeployment member; wrapping at least a portion of the harness about thedeployment member; positioning the deployment member adjacent the heart;and moving the deployment member about the heart in a manner so that theharness unwraps from the deployment member onto the heart as thedeployment member is moved about the heart.
 24. The method of claim 23additionally comprising rotating the deployment member while moving itabout the heart.
 25. The method of claim 23, wherein the deploymentapparatus comprises a second deployment member.
 26. The method of claim25, additionally comprising wrapping a portion of the harness about thesecond deployment member so that the harness is wrapped in a scrollfashion about the first and second deployment members.
 27. The method ofclaim 26 comprising simultaneously moving the first and seconddeployment members about opposite sides of the heart.
 28. A cardiacharness, comprising a plurality of modules adapted to be coupled to eachother, each of the modules comprising a plurality of spring elements.29. A cardiac harness comprising a plurality of modules, each modulehaving a first edge, a second edge, and a zip coupling mechanism forselectively drawing the first and second edges adjacent to one another.30. A cardiac harness, comprising first and second modules and a zipcoupler which connects said first and second modules to each other. 31.A cardiac harness configured to fit about a patient's heart, comprisinga base portion, an apex portion and a medial portion between the apexand base portions, the apex portion comprising a plurality of spiralshaped elongate members, each spiral shaped elongate member connected atone end to the medial portion and at the other end to a terminal member.32. The cardiac harness of claim 31, wherein the plurality of spiralshaped elongate members together form a generally conical shaped regionof the harness.
 33. A cardiac harness configured to fit about apatient's heart, comprising: a base portion; an apex portion; and amedial portion between the apex and base portions; the base portioncomprising interconnected spring elements that are oriented so that thecollective spring force around the circumference of the base portion isin a first direction; the medial portion comprising interconnectedspring elements oriented so that the collective spring force around atleast a portion of the circumference of the medial portion is in asecond direction substantially different than the first direction. 34.The cardiac harness of claim 33, wherein the second direction hassignificant spring force components in directions both transverse andparallel to a longitudinal axis of the harness.
 35. A cardiac harnesshaving a central cavity for receiving a portion of a patient's heartsuch that the harness contacts the wall of the heart substantiallythroughout said cavity, said harness having a plurality of protrusionsextending inwardly such that interference between the protrusion and thewall of the heart aids retention of said harness on said heart.
 36. Thecardiac harness of claim 35, wherein at least one of the protrusionscomprises a barb configured to pierce a portion of the heart wall. 37.The cardiac harness of claim 35, wherein at least one of the protrusionsexerts a biasing force against the heart wall when the heart is disposedin the cavity.